To know when the tanks are finished cycling, between now and check Nitrates if you want to. When you are confident that the amonia-converting bacteria are eating all the ammonia in a small amount of time (it's really that ammonia = 0 when you test it. Number of minutes is good information but not essential. You just want that zero when you take 5 ml out of the tank and test it.

Then you will start to see a nitrite spike - same thing with that. Then test the nitrates. If there are nitrates present in the water, note the level and if it's above 20 ppm do a large water change, say 50%. After you have one of the 3 10s cycled do those levels on the onther two.